U.S. Pat. No. 7,670,759 (Patent Document 1) discloses a method of processing a hardmask and a gate electrode after shrinking a resist pattern by etching. The method is described in detail with reference to FIGS. 2A to 2E. First, in a first step of the method, silicon oxynitride 2, polycrystalline silicon 3, a silicon oxide film 4, an organic antireflection film 5, and a resist film 6 are formed on a silicon substrate 1 (FIG. 2A). Next, in a second step, a resist mask 7 having a line and space (L&S) pattern is formed by exposure and development (FIG. 2B). Next, in a third step, a L&S pattern 48 is formed by etching the organic antireflection film 5 based on the resist mask 7 with plasma under a O2-containing gas (FIG. 2C). At this time, the resist mask is shrunk by O (oxygen) radical, and therefore, an effect capable of forming a mask having a finer dimension than that of the resist mask formed by the exposure and development is obtained. Next, in a fourth step, a hardmask 44 is formed by etching the silicon oxide film 4 with plasma under a CF4 gas with using the pattern 48 as a mask (FIG. 2D). Last, in a fifth step, a gate electrode 43 is formed by etching the polycrystalline silicon 3 with using the hardmask 44 as a mask (FIG. 2E). Also, Patent Document 1 discloses a method of preventing deformation and collapse of the resist mask 7 by adding a sulfur (S)-containing gas in the third step to form a polymer to be a passivation film on a side surface of the resist mask 7.
Further, as a method of preventing deformation and collapse of a resist, U.S. Pat. No. 6,942,816 (Patent Document 2) discloses a method of using Xe (xenon) as a gas for diluting a reactive gas such as oxygen or fluorocarbon.
Still further, although not directly relating to deformation and collapse of a resist, U.S. Pat. No. 6,841,484 (Patent Document 3) discloses a method of, when an electrode material of a multi-layered film used for an MRAM is etched by using a hardmask formed by a resist mask, removing a deposition on a side surface of a metal film by etching a top electrode layer under a fluorine-containing gas, and then, repeating to alternately supply a chlorine-containing gas and a rare gas to each layer of the electrode material on a bottom layer.